Discussion
In the lowest energy conformation of the compound below, how many alkyl substituents are axial ?
Answer: D
In the lowest energy conformation 0 alkyl substituents are axial.
Number the ring with the wedged methyl at C-1, the hashed methyl at C-2 and the hashed isopropyl at C-4. C-1 and C-2 carry groups on opposite faces: a trans-1,2 relationship, which can be diequatorial. C-1 and C-4 are also on opposite faces: trans-1,4, again diequatorial. C-2 and C-4 are on the same face: cis-1,3, which is also diequatorial.
All three pairwise relationships are compatible with equatorial positions, so one chair has every alkyl group equatorial, and that chair is far more stable than its ring-flipped partner with all three axial. (This substitution pattern is that of the menthane skeleton with all groups equatorial.)
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